本文選題：激光剝離-激光誘導擊穿光譜 + 剝離閾值��； 參考：《華南理工大學》2015年碩士論文

【摘要】：為了填補對貴重樣品原子分布進行原位、少損耗、快速且準確檢測技術的空缺,同時為了解決單脈沖激光誘導擊穿光譜技術(LIBS)在空間分辨率和靈敏度之間的矛盾,本文提出使用正交雙波長雙脈沖激光剝離-激光誘導擊穿光譜技術(LA-LIBS),解決現(xiàn)有技術中存在的相關問題,并基于該技術對不同銀飾品中的微量元素進行分析。首先,為了追求更好的剝離效果,準確把握樣品的剝離閾值和聚焦激光的焦點光斑尺寸的關系,本文提出一種簡便方法,基于聚焦激光束在焦平面上的分布為高斯分布的假設,理論推導激光能量與激光在樣品表面所燒蝕的坑洞半徑的關系,利用LA-LIBS實驗平臺測量出不同能量的脈沖激光在樣品表面燒蝕的坑洞半徑,并通過數(shù)值擬合來實現(xiàn)對聚焦激光束的焦點光斑尺寸和樣品剝離閾值的同時測量,測量誤差約為±10%。本文基于單臺Nd:YAG激光器,先后建立532+1064 nm和266+1064 nm波長組合LA-LIBS系統(tǒng),對銀樣品進行微區(qū)分析,并比較兩種系統(tǒng)各自的空間分辨本領和分析靈敏度。532+1064 nm波長組合下樣品表面燒蝕坑洞直徑為17μm,銅的檢出限為44 ppm;266+1064 nm波長組合下樣品表面燒蝕坑洞直徑為6.5μm時,銅的檢出限為37.4 ppm。另外,在相同激光脈沖能量,相同激光脈沖數(shù)下532 nm與266 nm波長燒蝕坑洞直徑大小對比,分別為25μm和17μm。通過對比得出,266 nm激光比532 nm激光擁有更好的剝離效果,266+1064 nm波長組合比532+1064 nm波長組合能獲得更高的空間分辨率和分析靈敏度。本文還通過研究銅324.75 nm譜線強度與銀328.07 nm譜線強度在1064 nm激光的焦點中心與樣品表面之間的不同距離的條件下的相關性,以及相同1064 nm激光脈沖能量、不同266 nm或532 nm激光脈沖能量下的相關性,發(fā)現(xiàn)兩個參數(shù)具有較高的線性性,因此可以采用內(nèi)標法,用銀328.07 nm的譜線作為內(nèi)標線,建立銅的校正曲線,從而降低或消除由于實驗參數(shù)變化而對信號強度及樣品定量分析結果產(chǎn)生的影響。正交雙波長雙脈沖LA-LIBS技術能夠在原位測量的情況下保證高空間分辨率和高分析靈敏度,適用于貴重樣品微區(qū)分析,同時還能應用在如工業(yè)生產(chǎn)檢測、環(huán)境實時檢測等不同的領域。
[Abstract]:In order to fill the gap of in situ, less loss, fast and accurate detection of atomic distribution in precious samples, and to solve the contradiction between spatial resolution and sensitivity of monopulse laser induced breakdown spectroscopy (LIBS), In this paper, the orthogonal dual-wavelength double-pulse laser stripping and laser-induced breakdown spectroscopy technique is proposed to solve the related problems in the existing technology. Based on this technique, trace elements in different silver ornaments are analyzed. First of all, in order to obtain a better peeling effect and to accurately grasp the relationship between the peeling threshold of the sample and the focus spot size of the focused laser, this paper presents a simple method, which is based on the assumption that the focus laser beam is distributed as Gao Si distribution on the focal plane. The relationship between laser energy and the radius of the hole ablated by laser on the surface of the sample was derived theoretically. The radius of the hole ablated on the surface of the sample by pulsed laser with different energy was measured by using the LA-LIBS experimental platform. The focus spot size and the sample stripping threshold of the focused laser beam are measured simultaneously by numerical fitting. The measurement error is about 鹵10. 0. Based on a single Nd:YAG laser, a combined wavelength LA-LIBS system of 532 1064 nm and 266 1064 nm was established to analyze the microregion of silver samples. The spatial resolution and analytical sensitivity of the two systems were compared when the sample surface ablation hole diameter was 17 渭 m under the wavelength combination of 1064 nm, and the detection limit of copper was 44 ppm, 266 1064 nm, when the sample surface ablation hole diameter was 6.5 渭 m. The detection limit of copper is 37.4 ppm. In addition, the diameter of ablated holes at 532 nm and 266 nm is 25 渭 m and 17 渭 m, respectively, at the same laser pulse energy and number of laser pulses. The results show that 266nm laser has better peeling effect than 532nm laser, and the combination of 266 1064 nm wavelength can obtain higher spatial resolution and higher analytical sensitivity than 532 1064 nm wavelength combination. The correlation between copper 324.75 nm line intensity and silver 328.07 nm line intensity at different distances between the focal center of the 1064 nm laser and the surface of the sample is also studied, and the same 1064 nm laser pulse energy is also studied. It is found that the two parameters have high linearity under different laser pulse energy at 266nm or 532nm. Therefore, the calibration curve of copper can be established by using the internal standard method and the silver 328.07 nm spectral line as the internal standard line. Thus, the influence of the change of experimental parameters on the signal intensity and the quantitative analysis results of the sample is reduced or eliminated. The orthogonal dual-wavelength dual-pulse LA-LIBS technique can guarantee high spatial resolution and high analytical sensitivity in the case of in-situ measurement. It is suitable for microanalysis of precious samples and can also be used in industrial production detection. Environment real-time detection and other different fields.
【學位授予單位】：華南理工大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：O433;TN249

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本文編號：1978768